import TreeTraversal.TreeNode;

public class CommonAncestor {
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(p == null || q == null){
            return null;
        }
        if(root == null || root == p || root == q){
            return root;
        }
        TreeNode left = lowestCommonAncestor(root.left,p,q);
        TreeNode right = lowestCommonAncestor(root.right,p,q);
        if(left != null && right != null){
            return root;
        }else if(left != null && right == null){
            return left;
        }else if(left == null && right != null){
            return right;
        }else{
            return null;
        }
    }
}
